Do spring-flowering bulbs inhibit the growth of other plants?

Question

Last winter I planted a large container with several layers of bulbs (crocus, muscari, narcissi, daffodils, tulips). I wanted to repeat this display next year, and emptying the container to retrieve the bulbs and repeating the process to replant them seemed like a double waste of time effort.

So I left the foliage to die down naturally, then cut it down and sowed annual flower seeds for a summer display.

This was not a success. The seeds germinated fine, but the seedlings stopped growing when they were a 2 to 3 inches (5 - 10 cm) tall and just "sat there doing nothing".

There were no obvious signs of disease or pest damage. After more than half a century of gardening, I don't think I made any "beginner mistakes" over watering, feeding, etc!

I wonder whether the bulbs themselves were inhibiting root growth in the seedlings. Bulbs certainly naturalize well under grass in the UK, but grass isn't exactly a "typical" plant species of course.

Answer 1

I've had this problem myself. It only seemed to occur in a large container which was pretty crammed with layers of different bulbs, and I concluded it was because there's insufficient soil room for the temporary planting placed in the top. Certainly, when I emptied it out, it was quite difficult to get the larger bulbs out, they were pretty much wedged together, and there were a number of offsets taking up space too. I have other containers that do have bulbs and summer planting, but it'll only be a few bulbs beneath.

You had narcissus/daffodils in the pot though, and they can exert an allelopathic effect on some plants, though I use a few dwarf daffodils in pots with winter, then summer bedding, and haven't experienced this problem.